In 1974, Dr. Rose Frisch coauthored a paper for the journal Science showing that weight loss “because of injudicious dieting or excessive athletic activity, or both” could disrupt the reproductive ability of women.
“That was her biggest idea,” said her colleague Dr. Robert Barbieri, chairman of obstetrics, gynecology, and reproductive biology at Brigham and Women’s Hospital. “If a woman was lean and trying to get pregnant, she’d advise her to eat some ice cream, or put butter on her vegetables.”
Lower fertility for women who were too thin, she believed, might be evolution’s signal that they shouldn’t attempt a pregnancy that could present dangers. “This could be nature’s way of protecting both mother and child,” she told the Globe in a 1979 interview when she described her studies of the athletes whose training interrupted their menstrual cycles.
She worked closely with Olympic-level athletes with little body fat who had trouble conceiving, and some named their daughters Rose in appreciation, according to her son, Henry.
Dr. Frisch, an associate professor emerita at the Harvard School of Public Health whose health had been declining, died Jan. 30 in the Cadbury Commons assisted living facility in Cambridge. She was 96 and lived in Cambridge most of her life.
“She was a very brave person, a creative thinker, and a free spirit,” Barbieri said.
Dr. Frisch’s early findings about weight and pregnancy were a key step toward later research that identified the hormone leptin, which helps regulate appetite, obesity, and puberty. Her subsequent studies found that moderate, regular exercise lowers a woman’s risk of breast cancer, reproductive system cancer, and late-onset diabetes.
“Your brain knows you will not be successful at reproduction if you don’t have enough fat,” she told the Harvard Gazette in 1998. “But too much fat increases the amount of estrogen in the body and can thereby raise the risk of getting cancer.” Leptin, which carries signals from fat cells to the brain, is “a fascinating molecule that ties together 25 years of research on food, fertility, exercise, hormones, and cancer risk.”
Dr. Frisch also advocated for exercise for young girls, saying it would help delay the onset of menstruation, which could prevent diseases later in life.
In 2002, she published “Female Fertility and the Body Fat Connection,” a book intended not for scientists, but for women who wanted to become mothers. A New England Journal of Medicine review noted that Dr. Frisch collaborated with “nutritionists, endocrinologists, exercise physiologists, ballet dancers, and athletic coaches,” and that “She made all of Boston, with its wealth of universities, students, and hospitals, her laboratory.”
Dr. Frisch, who received grants and awards throughout her career, also wrote a children’s book on nutrition called “Plants That Feed the World” and was passionate about population growth, as well as birth control and abortion rights. She spent many years with Harvard’s Center for Population and Development Studies.
Rose Epstein was born in the Bronx, N.Y., in 1918, the youngest child of Louis Epstein and the former Stella Skolnick, immigrants who had fled Russia. Her older brother Lee, who changed his last name, was the father of Linda Eastman, the late wife of Beatle Paul McCartney.
After graduating from high school, Dr. Frisch hitchhiked to Smith College, where she studied biology and graduated in 1938. While there she met David Frisch, a physicist, on a blind date. They were married in New York by his father, a Texas rabbi, and then both enrolled in the University of Wisconsin, where she received a doctorate in genetics and he worked toward a doctorate he completed later at the Massachusetts Institute of Technology.
During World War II, they moved to Los Alamos, N.M., for the Manhattan Project that developed the atomic bomb, and she worked for physicist Richard Feynman.
When the United States dropped atomic bombs on Japan, the Frischs “were very disappointed,” said their son, Henry, a University of Chicago physicist. “They really thought they’d been working on a chance for mankind to save itself.”
After the war, the Frischs moved to Carlisle before settling in Cambridge. David Frisch, who died in 1991, taught at MIT. Though she stayed home to raise their two children, Dr. Frisch was an avid reader and “intellectually interested in everything,” Henry said. “She was fun and she was funny. People really enjoyed being around her.”
When her second child reached middle school, Dr. Frisch began working as a research associate at Harvard University’s population center. According to her family, even though she had a doctorate, she was paid just a few dollars an hour because, her superiors told her, her husband’s salary could support her.
But Dr. Frisch wasn’t in it for the money, said her daughter, Ruth Dealy, an artist in Providence, and she wasn’t fazed by the “great deal of hostility” her ideas created among her mostly male peers.
“Her work was her mission,” her daughter said. “She had a very strong urge to correct what was wrong in the world.”
Dr. Frisch and her husband were strong proponents of nuclear disarmament who loved talking politics with each other and with friends. “I remember coming home from school and finding them in the living room with Tip O’Neill,” their daughter said. “They were both really left wing.”
Dr. Frisch also was a keen storyteller who made a lasting impression. The novelist Ann Patchett met her in 1993, when both were awarded yearlong fellowships at the Bunting Institute in Cambridge.
“She was a lovely woman, funny and kind, who was capable of making difficult science accessible,” Patchett wrote in an e-mail, recalling a presentation Dr. Frisch delivered on her research, as well as her stories about working on the Manhattan Project.
When Patchett began writing her 2011 novel “State of Wonder,” she based one of the main characters on Dr. Frisch. That character, a researcher named Annick Swenson who was developing a fertility drug, was “terrifying and controlling,” while Dr. Frisch was “loving and warm,” Patchett wrote. “So they certainly weren’t the same person. Still, when I was developing Dr. Swenson’s character . . . I was reminded of Rose’s work with fertility.”
Patchett borrowed Dr. Frisch’s physical characteristics as well. Both women were “small, soft, white-haired,” and also were “brilliant scientists who looked like somebody’s grandmother,” Patchett wrote.
Dr. Frisch’s granddaughter Sarah, a writer and Stegner fellow at Stanford University, was recently assigned to be Patchett’s guide when the author visited the campus. “It was a total fluke,” Sarah said. When they met, Patchett told her: “ ‘I’ve only known one other Frisch, a scientist named Rose.’ And I said, ‘That’s my grandmother.’ ”
A service will be held for Dr. Frisch, who in addition to her son, daughter, and granddaughter leaves three other grandchildren and three great-grandchildren.
“She was really fun, so direct and so incredibly sweet,” Sarah said. “Mostly she was just 100 percent herself, always.” She recalled that her grandmother was a practical joker with a great sense of humor who “loved to sit on the back porch and drink vermouth.”
Dr. Frisch played piano throughout her life, by herself and with other musicians. Her granddaughter Genevieve, a musician, recalled that every Sunday morning Dr. Frisch played her favorite piece, Bach’s “Chromatic Fantasy and Fugue.”
Music was “just a natural part of her, she thoroughly loved it,” Genevieve said. “She was always playing or humming or dancing, or talking about Mozart and Bach.”
Kathleen McKenna can be reached at firstname.lastname@example.org.